Class Test for IISc-II,

5 august 2013   

TIME: 55 minutes  —-     Total Marks 35

Section A

Objective {7 questions carry 7 marks, all to be answered}

1. Targets in X-ray tube are made of high atomic number metals. Examples are

A. Tungsten and Platinum              B. Nickel and Chromium                                                                                            C. Uranium and Plutonium            D. Sodium and Mercury

2. Electric and magnetic fields do not deflect which of the following

A. X-rays                    B. Y-rays

C. electrons              D. Cosmic Rays

3. Why K_a and K_b lines are produced  (chose only one appropriate answer)

A. electronic transitions                                                           B. Atomic collisions

C. Radioactive decay                                                                  D. Nuclear transmutation

4. Exactly why there is quantization of physical variables such as momentum, angular momentum, energy, orbital distance and speed?

A. wave-particle duality                                         B. Interference of waves

C. Particle acceleration to speed of light            D. Resistance experienced by particles in conductors

5. Cathode rays are streams of

A. electrons                                         B. x-rays

C. nucleons                                          D. high atomic number elements

6. Kirchhoff’s loop rule is based on?

A. Conservation of charge                 B. conservation of energy

C. conservation of baryon number D. conservation of lepton number

7. Kirchhoff’s Junction rule is based on?

A. Conservation of charge                 B. conservation of energy

C. conservation of baryon and lepton number D. conservation of azimuthal quantum number

Section B

Subjective {14 questions carry 2 marks each, all to be answered}

8. If threshold frequency is 5×10⁴ Hz whats the work function of the metal in eV or Joule?

9. 3 capacitors c₁=5 µF each are in series, whats their equivalent resistance?

10. 3 capacitors c₁=5 µF each are in parallel combination, whats their equivalent resistance?

11.  If a potential difference of 3 V is applied at two ends of a 60 cm long metal wire with current density = j = 10^-7 A/m² whats conductivity of the wire?

12. In a Wheatstone bridge if P = 5 Ω, Q = 10 Ω are the resistors in one arm, and R = 15 Ω what would the unknown resistor S in the 2^nd arm be?

13. If work function of a metal is 50eV whats the maximum kinetic energy of any e^– be given a light of energy of 100 eV falls on the metal? Whats the stopping potential?

14. Name 4 sources of electric power that can be harnessed for Household applications.

15. If 3 cells of emf ε₁,  ε₂ , ε₃ are connected in series with their + and – terminals connected in sequential order and each has a back-emf ε₁^’,  ε₂’, ε₃^’ whats the equivalent emf of the series?

16. If a cell ε₁ = 5 V & ε₂ = 5 V are connected in parallel with zero internal resistance for both whats their equivalent emf?

17. For principal quantum number 5 whats the speed of an electron in a Hydrogen atom?

18. What would the wavelength of a radiation of energy 50 MeV be?

19. For a free electron of speed 0.1 c with c = 3 x 10⁸ m/s  what is the de-Broglie wavelength?

20. If a conductor of length 50 cm and area of cross section 1 mm² carries a current of 2 Amp, when a battery of emf with ideal terminal voltage 50 V is connected across, what the resistivity of the wire is?

21. In Thomson’s e/m experiment the e^– is going in a circle of circumference 1 m then whats the speed of the e^– if magnetic field intensity B is 10 Tesla. (Tesla is SI Unit of magnetic field intensity)